By contrast, in the rd1 mouse model of RP, deletion mutations in the rod-specific Pde6β gene led to increased H3K27me3 levels in postnatal retinas, while treatment with the HMT inhibitor DZNep delayed rod death by downregulating NRL and its downstream target NR2E3 to protect rods (Zheng et al., 2018). The gene discussed is PDE6B; the disease is retinitis pigmentosa 1.